Stephen H. Schneider, an internationally noted climate scientist at Stanford University who gathered powerful evidence for global warming that made him a fierce advocate for policies to combat climate change for four decades, died Monday while on a flight to London from a science meeting in Stockholm.

Although he earned his doctorate in mechanical engineering and plasma physics, Dr. Schneider's early interest in the physics of Earth's atmosphere led him into climatology research, and within three years he and a colleague published their first evidence of the effects of carbon dioxide on rising global temperatures.

In 1975, he founded the international science journal Climatic Change, and remained its editor in chief until his death.

As a restless and committed science researcher, Dr. Schneider believed that continued interaction between the public and scientists was crucial to democracy. He wrote several books on the effects of climate change and his public advocacy was welcomed by many in the scientific community but was anathema to those who opposed his views.

In 1972, he was awarded another postdoctoral fellowship, this one at the National Center for Atmospheric Research in Boulder, Colo., where he remained until 1996 as a member of the NCAR scientific staff and founder of the center's Climate Project.

In 1996, Stanford recruited him for its faculty.

Dr. Schneider was a science consultant to every president, from Richard Nixon to Barack Obama and, in 1992, won a MacArthur Foundation "genius" award.

He had aggressively battled a rare form of cancer called mantle cell lymphoma, and chronicled his fight to survive in a 2005 book called "The Patient from Hell."

He is survived by his wife, Stanford biologist Terry Root, with whom he jointly won the national Conservation Achievement Award in 1993 from the national Wildlife Federation.